The present invention relates generally to bicycles and specifically to bicycle frames.
Bicycle frames have been manufactured for many years in a variety of configurations and using a variety of materials. Today, many bicycle frames have a configuration called a “diamond frame,” which includes a main frame and a rear frame. The main frame typically includes a head tube, a top tube, a down tube, and a seat tube. The rear frame typically includes a pair of seatstays and a pair of chainstays. A pair of rear forks commonly connects opposing pairs of seatstays and chainstays, and a bottom bracket commonly connects the down tube, seat tube, and chainstays to provide a location for a crank assembly. Some frames omit the top tube to create a “step-through frame.”
In order to provide steering function, bicycle frames typically include a front fork pivotally coupled to the head tube. Upper and lower head tube bearings are often used to facilitate rotation of the front fork relative to the head tube and to transmit force from the front fork to the main frame. The location rearward of the lower head tube bearing is a place of high stress on most bicycle frames.